MySQL 5.7: Inconsistent Results with GROUP BY and HAVING Clauses in Complex Queries
This might be a silly question, but I'm stuck on something that should probably be simple. I've been banging my head against this for hours. I've searched everywhere and can't find a clear answer... I'm working with an scenario with MySQL 5.7 where my query returns inconsistent results when using `GROUP BY` along with `HAVING`. The query is intended to aggregate data from a sales table, filtering out any entries based on total sales per product. Here's the query I'm using: ```sql SELECT product_id, SUM(sales_amount) AS total_sales FROM sales GROUP BY product_id HAVING total_sales > 1000; ``` The goal is to retrieve only those products that have total sales exceeding 1000. However, when I run this query, I occasionally receive products that have total sales below this threshold. I've even tried running the same query multiple times in a row and noticed that sometimes the results change. To troubleshoot, I checked for any potential data anomalies, such as duplicate entries, but everything appears to be clean. I also tried using `DISTINCT` in the `SELECT` clause, but that didn't help resolve the scenario. Here’s a sample of my sales data: ```sql INSERT INTO sales (product_id, sales_amount) VALUES (1, 500), (1, 600), (2, 200), (2, 300); ``` When I run the initial query after these inserts, it returns both product 1 and product 2, which doesn’t make sense since their total sales should be 1100 and 500 respectively. I've considered potential issues with transaction isolation levels, but I'm running the default settings. Is there something I could be missing here with how MySQL handles the aggregation and filtering? Any insights would be greatly appreciated! This is part of a larger application I'm building. Thanks in advance! I'm working on a application that needs to handle this. How would you solve this? I've been using Sql for about a year now.